Production of branched-chain flavor compounds from hydrolysis of pork myofibrillar protein by optimizing the inoculation of Limosilactobacillus fermentum YZU-06 and Staphylococcus saprophyticus CGMCC 3475

Abstract

This study aimed to develop a mixed starter of Limosilactobacillus fermentum YZU-06 and Staphylococcus saprophyticus CGMCC 3475 isolated from Jinhua ham for enhancing the production of branched-chain flavor compounds from pork myofibrillar protein. Different ratios of mixed strains (3:1, 2:1, 1:2, and 1:3) and single strains were employed to incubate with myofibrillar protein extract to detect viable counts, pH, proteolysis, and branched-chain volatiles at 24, 48 and 72 h of incubation. The result showed that the inoculated strains had acid-producing characteristics and bacterial suitability. The mixed starter of 2:1, 1:2, and 1:3 treatments exhibited a higher degree of protein degradation, as indicated by a 90% similarity through cluster analysis of myofibrillar protein in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Compared to the other treatment groups, 2:1 group showed a significantly higher peptide content of 123.58 μg/mL and a greater concentration of free amino acids (236.67 mg/L). Furthermore, 2:1 group obtained the highest levels of 3-methylbutanal (56.06 μmol/L), 2-methylpropanal (1.76 μmol/L), and 2-methylbutanal (0.48 μmol/L). Our findings emphasize the importance of appropriate proportions of L. fermentum YZU-06 and S. saprophyticus CGMCC 3475 for the starter to produce branched-chain flavor compounds of meat products.